/*! This file is auto-generated */ .wp-block-button__link{color:#fff;background-color:#32373c;border-radius:9999px;box-shadow:none;text-decoration:none;padding:calc(.667em + 2px) calc(1.333em + 2px);font-size:1.125em}.wp-block-file__button{background:#32373c;color:#fff;text-decoration:none} Problem 30 Prove the anticommutative proper... [FREE SOLUTION] | 91Ó°ÊÓ

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Prove the anticommutative property of the vector cross product, \(\mathbf{A} \times \mathbf{B}=-\mathbf{B} \times \mathbf{A}\), using the expressions for the components of the cross product.

Short Answer

Expert verified
The cross product is anticommutative: \( \mathbf{A} \times \mathbf{B} = -\mathbf{B} \times \mathbf{A} \).

Step by step solution

01

Write Down the Cross Product Expressions

To prove the anticommutative property of the cross product, first write the expression for the cross product of two vectors \( \mathbf{A} = (A_1, A_2, A_3) \) and \( \mathbf{B} = (B_1, B_2, B_3) \). The cross product \( \mathbf{A} \times \mathbf{B} \) is given by:\[\mathbf{A} \times \mathbf{B} = (A_2B_3 - A_3B_2, A_3B_1 - A_1B_3, A_1B_2 - A_2B_1)\]
02

Reverse the Order of the Cross Product

Next, write the expression for the reverse order \( \mathbf{B} \times \mathbf{A} \):\[\mathbf{B} \times \mathbf{A} = (B_2A_3 - B_3A_2, B_3A_1 - B_1A_3, B_1A_2 - B_2A_1)\]
03

Compare the Component Expressions

Compare each component of \( \mathbf{A} \times \mathbf{B} \) and \( \mathbf{B} \times \mathbf{A} \). For each component, note that:- The first component of \( \mathbf{A} \times \mathbf{B} \) is \( A_2B_3 - A_3B_2 \), while the first component of \( \mathbf{B} \times \mathbf{A} \) is \( -(A_2B_3 - A_3B_2) \).- The second component for \( \mathbf{A} \times \mathbf{B} \) is \( A_3B_1 - A_1B_3 \), while for \( \mathbf{B} \times \mathbf{A} \) it is \( -(A_3B_1 - A_1B_3) \).- The third component for \( \mathbf{A} \times \mathbf{B} \) is \( A_1B_2 - A_2B_1 \), compared to \( -(A_1B_2 - A_2B_1) \) for \( \mathbf{B} \times \mathbf{A} \).
04

Formulate the Anticommutative Property

Since each component of \( \mathbf{B} \times \mathbf{A} \) is the negative of the corresponding component in \( \mathbf{A} \times \mathbf{B} \), the vector cross product is anticommutative. Thus:\[\mathbf{A} \times \mathbf{B} = -(\mathbf{B} \times \mathbf{A})\]

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Key Concepts

These are the key concepts you need to understand to accurately answer the question.

Anticommutative Property
The anticommutative property is an essential concept in vector algebra, primarily seen in the vector cross product. It states that changing the order of the vectors in a cross product results in a vector that points in the opposite direction. In mathematical terms, the cross product of vectors \( \mathbf{A} \) and \( \mathbf{B} \) satisfies \( \mathbf{A} \times \mathbf{B} = -\mathbf{B} \times \mathbf{A} \).
This means that flipping the order of the two vectors not only changes their orientation but effectively reverses the sign of the resulting vector. Hence, the cross product is anticommutative. This property is unique compared to other algebraic operations like addition and multiplication, which are typically commutative (i.e., \( a + b = b + a \) or \( ab = ba \)).
The anticommutative nature of the cross product is crucial in physics and engineering, where directionality and orientation play significant roles in rotational dynamics and electromagnetic theory.
Recognizing and applying this property can simplify calculations and resolve potential errors when dealing with vector operations. Always remember, swapping the vectors in a cross product reverses its direction.
Vector Algebra
Vector algebra is a branch of mathematics dealing with quantities that have both magnitude and direction. It includes operations, like addition, dot product, and cross product, essential for calculations in physics and engineering.
The cross product, in particular, differs from scalar multiplication, as it results in a vector perpendicular to the original vectors. This perpendicular vector has a magnitude equal to the area of the parallelogram that the two vectors span.
Unlike algebra with numbers, vector algebra requires attention to direction, as evidenced by the anticommutative property of the cross product. When performing vector operations:
  • Pay attention to each vector's direction and magnitude.
  • Use the right-hand rule to determine the direction of the cross product.
  • Ensure correct component-wise operations to avoid errors.
Vector algebra is fundamental for understanding physical phenomena, from trajectories of moving objects to forces acting on structures. Mastering these concepts can help solve complex problems that are common in scientific studies.
Component Notation
Component notation is a method of expressing vectors in terms of their individual parts or components. Representing vectors with their components makes it easier to perform operations like addition, dot product, and cross product, particularly when applying the anticommutative property.
For two vectors \( \mathbf{A} = (A_1, A_2, A_3) \) and \( \mathbf{B} = (B_1, B_2, B_3) \), the cross product \( \mathbf{A} \times \mathbf{B} \) is calculated as:
\[\mathbf{A} \times \mathbf{B} = (A_2B_3 - A_3B_2, A_3B_1 - A_1B_3, A_1B_2 - A_2B_1)\]
Here, each component of the resulting vector is derived from a specific combination of the components of \( \mathbf{A} \) and \( \mathbf{B} \). This makes component notation a powerful tool for dissecting a vector's properties and performing vector operations accurately:
  • Each vector component reflects a projection in one direction.
  • Operations are performed on corresponding components.
  • This method allows clear visualization of how vectors interact in different directions.
Using component notation effectively not only aids in calculation but also enhances understanding of vector interactions and behaviors in various fields.

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